Zero turning radius lawn mowers have enjoyed significant commercial success as the benefits of their maneuverability and performance become increasingly known. In a typical embodiment, a zero turning radius mower includes a mower deck mounted on a pair of drive wheels, each of which is independently operated by a hydraulic pump coupled to the mower's engine. A corresponding motor is provided for each drive wheel, each motor being powered and controlled by one of the pumps.
In the embodiments known to date, each pump typically includes a control lever for regulating fluid pressure and direction to its corresponding motor so that the drive wheels can be independently controlled. This allows each drive wheel to be rotated at a variable speed in both the forward and reverse directions. In this manner, the mower may be steered by controlling the speed and direction of the two drive wheels.
Accordingly, the operator can move both control levers forward to drive the mower forward, or can move both levers backward to drive the mower backward. Alternatively, the operator can move one control lever forward while keeping the other in its upright neutral position. This will cause one drive wheel to be driven forward while the other drive wheel remains stationary, enabling the mower to execute a zero radius turn in which the mower pivots about a vertical axis passing through the stationary wheel. Additionally, the operator can move one control lever forward and the other control lever rearward. This causes one drive wheel to be driven forward and the other drive wheel to be driven in reverse, enabling the mower to execute a spin turn in which the vehicle pivots about a vertical axis located midway between the two drive wheels.
As is appreciated by the art, lawn mowers of this type are highly maneuverable. Zero radius turns or spin turns are particularly advantageous when an operator comes to an edge of a yard during mowing operations and wants to turn around and mow in the opposite direction. The operator can simply execute a zero radius turn and begin mowing back in the opposite direction. Furthermore, spin turns are advantageous when mowing in tight spaces or when maneuvering out of confined spaces such as a shed or garage.
In many commercial mowers however, the operator does not sit on the mower but instead walks behind the mower or stands on a platform directly or indirectly attached to the mower deck. This makes the use of the dual control levers somewhat problematic, since the operator must use the control levers to steady himself as the mower turns and bounces over uneven ground. When the mower pitches forward or rolls to one side during operation, the operator may reflexively push one or both of the control arms in an unintended direction, thereby causing the mower to be driven off course.
A need therefore exists for a control mechanism for zero turning radius mowers that is better adapted for use with walk behind or stand-on power mowers. The present invention addresses that need.